The Elmer's Shack

Ohm's Law

"The Elmer's Shack" is the brainchild of our very prolific writer Cory Sickles, WA3UVV. The idea behind it is to try and encourage a number of our experienced members to become Elmers, in the verbal sense, to our readers that could use the information provided. We have members that have experience in RF, DXing, antennas, soldering, computers, contesting, and many other disciplines within amateur radio. This section is an open invitation for them to share their knowledge and experience with those who merely have an interest in amateur radio, are fully licensed, or somewhere in between.

D-I-Y Links

Club member, Michael Weldon, KB2UMJ, has some helpful DIY projects on his website

Jim Wright, N2GXJ

Congratulations on getting your first HF Radio! Now What?

Thank you Santa! And congratulations! You’ve just got your first HF radio, and no matter what your license class is, you’re anxious to attach some kind of antenna to it, at least to hear what’s happening on the “ham bands”, and to maybe push that TX button up on your authorized portion of 10 meters for the first time to see if there’s anyone out there that can hear you!But the antenna choices are bewildering! Where to start? Vertical, horizontal, so many choices! It’s “analysis paralysis”, so much to learn, so much advise, so many technical details, all so confusing.

I just want to do something, but I don’t want to do the wrong thing, what should I do? – Help!Well, the great news is that you’re not alone. We all went through this, and the amazing lesson we learn is that you don’t have to be perfect, that it is OK to experiment, that it doesn’t have to cost a lot of money, and there are members of our club who are willing to help, if asked. Let’s step back for a moment, take a deep breath, and see what our options are.Before you buy that “fancy” antenna, take some advice from the ARRL, and read this article http://www.arrl.org/building-simple-antennas. You’re going to encounter manufacturer claims that are, well, how to say this politely, designed to sell you their product, sometimes with wild claims. This is something that the ARRL, and us, your fellow Hams, would like to caution you about. For example, you generally won’t see claims of antenna gain in advertisements in QST magazine, because they have a strict policy that requires the manufacturer to prove it before they will publish it.What I’m suggesting is maybe trying something simple first, while you shop around, and visit and talk with other hams for a while, to see what works best for them, and what doesn’t, before spending big money on something like an outdoor antenna system that you’re not likely to know that much about yet anyway.So, now that I have a radio, but I don’t have an antenna yet, what would you recommend I do?There are two suggestions, and they’re both simple.First: As a member of the GCARC, you can be given the access and security alarm codes for our clubhouse trailer, and you can try out your new radio with both wire and beam antenna systems that we have set up out there! Also, you can get in-person help from a fellow ham on how to set up and operate that new radio. Starting in January, each month, on the first Saturday after our Wednesday general membership meeting, we’ll be having “Tech Saturdays” mornings out at the clubhouse. You can read more about this on our website on the "Tech Saturdays" page. There should be people there who can help you figure out “how does my radio work”, and help you get it on the air. So that’s my first suggestion. Make it easy on yourself. Bring your radio out for a "Tech Saturdays" morning, and with some help from other club members, see how it works with the different antennas available to try out at the clubhouse. Then after that, you can borrow the clubhouse setup whenever you want until you have something set up at home that you’d like to try and use.Second: If you’ve tried the first suggestion, and now want to also be able to use your radio at home, you have two basic choices for your antenna: you can buy something, or build something. This being ham radio, I’d actually suggest building your first antenna, rather than buying one. But you’re welcome to buy or build as you desire. That’s part of the joy of ham radio!So, from here on out, this article is just a recommendation for how I would suggest you would get started with your own home antenna. Others may, and probably will, have other opinions. That’s OK. I recognize there are many ways to accomplish the same goal, and this is just one of them. I’m not looking to be “flamed” by those who have different suggestions, or who might do it differently. I am just describing what worked for me, and am putting this out there for your consideration.The recommended antenna is a really simple, inexpensive, and very forgiving design made from cut lengths of insulated wire attached in the center to a thing called a balun (which I’ll explain later). They call this antenna a multi-band or fan dipole. You don’t have to be perfect when putting it up, which makes it great for a starter antenna.We’ll install this fan dipole up in the attic, so it is both protected from the weather, and won’t be able to be seen by prying neighbors. And we’ll build it using simple insulated wire, rather than tubing, so you might be able to save some cost by using materials that you or other club members might just have laying around. Your FCC license allows you to experiment with wire antennas for Ham radio like this, so why not have a little fun?This antenna, is going to be in the attic you say? Yes. As described in the ARRL article http://www.arrl.org/indoor-antennas, if you have some sort of attic in your home, apartment or condo, you’re in luck. Attics are great locations for indoor antennas. They’re protected from the wind and weather, and from the prying eyes of neighbors. Let’s get something up there and try it!When it comes to what to use to connect your radio to the antenna, don’t sweat it too much. This is HF radio, not UHF/VHF that we’re talking about. If you use a balun at the antenna as I suggest (explained later), you won’t need to use ladder line, making it very simple, and it will work just fine, to just use coax cable for the connection. Don’t worry about the precise length of coax – just buy or borrow a length long enough to get from your radio to the attic, with spare (that you can coil up in the corner somewhere).If your radio has a built-in antenna tuner, and many new ones do, you’ll just connect the coax to the connector on the back of your radio. If it doesn’t, then connect it to the external antenna tuner you have separately attached to your HF radio. The other end goes up into the attic to connect to the balun in the center of the dipole antenna, as described next.So what do I need to build this fan dipole?

1. A coax cable with male connectors each end, one end to attach to radio (or external tuner), and other end to attach to the bottom of the balun that will be at the center of our antenna. You run this from your radio up to the balun in the center of your attic. They typically come with connectors pre-installed, which makes it easier. The connector type should match what you need to connect to the back of your radio (or your external tuner, if one is not built into your radio), and to the balun described next.

2. A 1:1 current balun, that the antenna wire is attached to on the sides, and the coax cable connector screws into on the bottom. You hang the balun high in the center of your attic from the underside of the roof. The balun does triple duty for us as 1) a center point to attach each half of the wire antenna to, 2) a center point to attach a coax cable to, and 3) as a balanced-to-unbalanced transformer match between the wire antenna and the coax that also helps choke unwanted RF from running down the outside of the coax back into your shack. I bought one from Ham Radio Outlet in Delaware that was made by a company called RadioWavz that has threaded posts on the sides to make it easy to attach the wires to. Other choices are available.

3. One or more pairs of equal length 14 gauge insulated and stranded (not solid) wire, cut to specific lengths. You can find such at Lowes in the electrical section. I say stranded, not solid, because it is easier to work with. To make the equal length pair, you cut one piece to the full length specified, and then cut it in half, attaching each equal length half of the cut to opposite sides of the balun in the middle. My favorite web site for referencing wire antenna lengths is http://www.chem.hawaii.edu/uham/antennas.html. To make it easy, and to allow for a tiny bit of inevitable droop when trying to make them straight and level in the attic, you can follow the directions below, as a start, for your three wire antenna lengths. The wires are slightly longer than necessary on purpose, to accommodate the droop, but also to facilitate tuning by an expert by wrap-back length shortening, rather than adding, should you so desire to do so (you shouldn’t have to, but it’s still an option).

For 40 Meters, that also works on 15 Meters and on 6 Meters, you don’t have to be that exact. Cut one piece approximately 67 feet long, and cut in middle to make two equal 33 feet 6 inch halves to attach to the center balun. If you just put up this one dipole length, and none of the others, this one should let you talk with stations for several hundred miles up and down the East Coast fairly well during the day, and even better in the late afternoons and early evenings.

For 20 Meters, cut one piece 34 feet long, and cut in middle to make two 17 foot long halves to attach to the center balun. If you’re putting up just one dipole in the attic, this might be the one to put up. Whereas the higher frequencies usually give out after dark, there are usually stations on this band at all hours of the day and most of the night, particularly on 14.070 MHz which is the frequency commonly used for PSK digital communications (one of my favorites).

For 10 Meters, be a little more precise, and cut one piece 16 feet 10 inches, and cut in middle to make two 8 feet 5 inch long halves to attach to the center balun. If you’re just putting up this dipole, this one will let you have morning Europe contacts and afternoon West Coast contacts – but only temperamentally. Temperamentally because it’s up to somewhat unpredictable solar conditions for when this band is “open”, and when it is not. It’s kind of like fishing, you never know what you’ll catch unless you try on this band. Your attic dipole is high above ground, relative to a 10M wavelength, so when the band is open, you should be able to make some long distance contacts on this band.

4. Some kite string, or clothes line, or other rope to tie things off up in the attic. Being in the attic, you have the advantage of not having to worry about the wind and weather; e.g. your antenna and supports are not going to get wet so you can ignore the extra steps you’d have to take to make this antenna and its connections and supports weather-proof for hanging outdoors.

When you’re done, it might look like this:

1:1 Current Balun

Attic Dipole

Attic Dipole String

Attic Dipole - Top View

A YouTube video showing WD0AKX constructing such an antenna can be seen here: https://www.youtube.com/watch?v=8KHzsKYsZL0. You get the idea. He put his outside. We’ll put ours in the attic. And because we put ours in the attic, we don’t have to use those spacers between the wires that he built. Like he shows early in the video, you can run the wires off in different directions, instead of using spacers, which is really easy to do in the attic. So that’s what we’ll do.

Just put the balun up near the roof in the center of your attic and run the longest wires straight as far as you can in opposite directions from each other, then angle them around to make it all fit up there. The shorter pairs of wires, run those as far as you can in a straight line in opposite directions, again with the balun in the middle, but to different tie down points at a slightly different angle than the other wire pairs you put up.

Use kite string, or rope to tie to the end of the wire (can make a small knot at the end of the wire to attach the kite string to) and stretch out and attach to a convenient roof support in that direction in your attic. For the short antenna (the 10M antenna), if you can, you might want to stretch it broadside to the direction of Europe, as shown in the picture. From where we are in NJ, when the band is open, this will improve the strength of received signals from both Europe and South America, though any direction will do. For now, it’s just important to get something up there, and get on the air! You can always experiment later.

Also note that in the video, he added a wire for 6M, but says in the video he didn’t need it (because the 40M dipole already can be used with that band and an antenna tuner). To make things simpler for our antenna, we won’t include it. I don’t think you’ll miss it. That band isn’t used much, and having more wire pairs makes it harder to attach the wire bundle to each side of the balun.

Once you have it built, and installed, you can borrow an expert’s “SWR meter” to measure how perfect it is on the different bands, but as shown in the video, with your antenna tuner, it probably won’t matter much. After that, you’re on the air, and then off to experimenting with other antenna types no doubt, like back yard verticals, and various forms of wire or yagi beams.So that’s it! Once again, congratulations on your new radio! Hope to catch you on the air soon!

1. Use “flat top” LEDs as seen in the picture. “Flat tops” have a wide angle of light dispersion, upwards of 140-180 degrees. DO NOT use typical “rounded top” LEDs, as they have a low angle 15-45 degrees of light dispersion, which creates a spot or beam effect.

2. Use LEDs with several thousand “mcd” in intensity. Many of these "flat top" LEDs are available on ebay and other sources, for very low cost. 3. What are the advantages of LEDs over incandescent bulbs? The LEDs will likely never burn out and will outlast the rig, or even outlast you. In some transceivers, they also do not dim when keying up.Installing LED based on a 13.8 VDC source: 1. A 560 ohm drop resistor must be soldered to the anode (longer lead) of the LED, then solder the resistor to the positive lead of the voltage source. The 560 ohm resistor value is a generic value that should cover all the LED color ranges. 2. Connect the cathode (shorter lead), to the negative side of the voltage source (shrink tubing may be needed for both leads).

Installing LEDs based on voltage source other than 13.8 VDC: If you have a voltage source other than 13.8 VDC, you can use this LED Calculatorto calculate the resistor that is needed for your voltage source. You will need the LED “Typical Forward Voltage” and “Typical Forward Current”. For “Typical Forward Current”, you can just use 20mA.

For “Typical Forward Voltage”, it varies by LED color.Basic values for these “Flat Top” LEDs are the flowing:

Red, yellow, orange, amber = 3.0 VDC Blue, green, clear white, warm white = 3.4 VDC Pink, Purple = 3.2 VDC Some LED color forward voltages, may vary slightly from above, but are usually available from the vendor where you purchase them from.Voltage source should be measured at the leads that connect to the LED. Hints: As mentioned above, a 560 ohm resistor is a common value and good generic value for 13.8 VDC source. If you do not have a 560 ohm, you can use higher values, like a 1K ohm, at a slightly reduced intensity. Don’t lose sleep trying to find a 560 ohm, if you do not have one. The reduced intensity might not be noticeable.Many people love the different color LEDs, because they look cool on the meter.Blue seems to be especially popular.Ice white seems to best bring out the colors of the meter.Do not use clear white. You will not like it. Warm white is best if you are a purist and use vintage rigs. Warm white LEDs are as close to replicating the “incandescent” color of typical light bulbs, as you can get. They also look much better in vintage equipment. Some SWR meters have very small lamps. The LEDs mentioned above are based on the very common 5mm LED. If you have a meter that has a very small lamp and a 5mm will not fit, you can get the same “flat top” in a 3mm size. Vinnie Sallustio - N4NYY